Cobalt(II) hydride
# Cobalt(II) hydride

Cobalt(II) hydride is an inorganic compound with a chemical formula $CoH_2.$ It has dark grey crystals. It oxidizes slowly in air and reacts with water.

Two forms of cobalt(II) hydride exist under high pressure. From 4 to 45 GPa there is a face-centred cubic form with formula CoH. This can be decompressed at low temperatures to form a metastable compound at atmospheric pressure. Over 45 GPa a cobalt(II) hydride $CoH_2$ also crystallises in a face-centred cubic form.

## Preparation

Cobalt(II) hydride can prepared by reacting phenylmagnesium bromide and cobalt(II) chloride in hydrogen gas:

    $CoCl_2$ + 2 $C_6H_5MgBr$ + 2 $H_2$ → $CoH_2$ + 2 $C_6H_6$ + $MgBr_2$ + $MgCl_2$
